If you’re new to working with flash, especially when shooting portraits, all of the different terms for different lights can be quite confusing. With no context whatsoever, “key”, “fill”, “rim”, “kicker”, etc. are all kind of vague and non-descript. Once you understand the purpose for each, though, the naming convention becomes quite obvious.
In this video, photographer John Gress walks us through each of the different terms used for different types of lighting position, as well as how and why each of them are used when shooting portraits. He also mentions some of the names different photographers seem to use for the same thing – often a big cause of confusion judging by some of the posts I see on social media.